Q. Given that u=3w4−5, find dwd(4w2−sinu) in terms of only w.Answer:
Identify Function and Rule: We need to find the derivative of the function 4w2−sin(u) with respect to w. To do this, we will use the chain rule, which states that the derivative of a composite function is the derivative of the outer function times the derivative of the inner function. In this case, the outer function is 4w2−sin(x) and the inner function is u=3w4−5.
Differentiate Outer Function: First, we differentiate the outer function with respect to u, treating w as a constant. The derivative of 4w2 with respect to u is 0, since w is treated as a constant and the derivative of −sin(u) with respect to u is −cos(u).
Differentiate Inner Function: Next, we differentiate the inner function u=3w4−5 with respect to w. The derivative of 3w4 with respect to w is 12w3, and the derivative of −5 with respect to w is 0. So, the derivative of u with respect to w is 12w3.
Apply Chain Rule: Now, we apply the chain rule by multiplying the derivative of the outer function with respect to u by the derivative of the inner function with respect to w. This gives us (0−cos(u))×12w3.
Simplify Expression: Simplify the expression by distributing the 12w3 across the terms inside the parentheses. This results in −12w3⋅cos(u).
Express Derivative in Terms of w: Finally, we need to express the derivative in terms of w only. Since u=3w4−5, we substitute u back into the expression −12w3⋅cos(u) to get −12w3⋅cos(3w4−5).
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